This application incorporates by reference Taiwanese application Serial No. 89211856, Filed Jul. 10, 2000.
1. Field of the Invention
The invention relates in general to an automatic document feeder (ADF), and more particularly to an ADF capable of releasing jammed papers.
2. Description of the Related Art
Having the advantage of transmitting documents continuously, ADFs are widely used in photo-copy machines, facsimile machines, printers, and image scanners.
However, the problem of paper jam is a barrier of the development and application of ADFs. Many reasons can cause paper jam. Ceasing the document transmitting process suddenly is one of the main reasons. Some other reasons are more related to feeding improper document. For example, documents with improper thickness (too thick or too thin), moisture (documents with high moisture are too soft while documents with low moisture are too hard) or size or rugged documents often cause paper jam.
Typically, there is special design for easily removing the jammed documents in an ADF. Referring to FIG. 1, a conventional ADF 100 is shown. The ADF 100 contains at least three roller sets including an ADF roller set 102, a first feeding roller set 104, and a second feeding roller set 106. While the document is forwarded, it is transmitted along the transmitting directions 130a, 130b, and 130c and is passed through the ADF roller set 102, the first feeding roller set 104, and the second feeding roller set 106 sequentially. The appearance of the ADF 100 typically includes an upper cover 108 and a main body 110. The upper cover 108 can be opened along the direction shown by the arrow 112. The roller of the ADF roller set 102 is rotatably mounted to the upper cover 108 and the idle pulley 104b of the first feeding roller set 104 is also rotatably mounted to the upper cover 108.
Therefore, the ADF roller set 102 and the first feeding roller set 104 can be easily released by opening the upper cover 108 along the direction of the arrow 112. Consequently, the paper jammed in the ADF roller set 102 and the first feeding roller set 104 can be easily removed.
However, while the paper is jammed in the second feeding roller set 106, it is rather hard to be removed either along the paper transmitting direction 114 or anti-paper transmitting direction 116. Paper can be even torn up and a portion thereof is left inside the ADF 100. Hard removing of the paper jammed in the second feeding roller set 106 is mainly caused by the damping produced by the motor 120. Damping results from the magnetic force between the stator (not shown) made of magnet and the rotor (not shown) made of coil in the motor 120. The magnetic force generates great resistance while the motor 120 is driven. Further more, damping produced by the motor 120 is enhanced by the speed down design of the gears of the driven machinery. So the jammed paper in the second feeding roller set 106 is hard to be removed no matter in which direction.
Another conventional ADF is as shown in FIG. 2. The ADF in FIG. 2 contains at least three roller sets including an ADF roller set 202, a first feeding roller set 204, and a second feeding roller set 206. When the document is forwarded, it is transmitted along the transmitting directions 230a, 230b, and 230c and is passed through the ADF roller set 202, the first feeding roller set 204, and the second feeding roller set 206 sequentially. The first feeding roller set 204 and the second feeding roller set 206 are connected by a transmission belt and are driven by a motor 214 indirectly. The appearance of the ADF 200 typically includes an upper cover 208 and a main body 210. The upper cover 208 can be opened along the direction shown by the arrow 212. The roller of the ADF roller set 202 is rotatably mounted to the upper cover 208 and the idle pulley 204b of the first feeding roller set 204 is also rotatably mounted to the upper cover 208.
Therefore, the ADF roller set 202 and the first feeding roller set 204 can be easily released by opening the upper cover 208 along the direction of the arrow 212. Consequently, the paper jammed in the ADF roller set 202 and the first feeding roller set 204 can be easily removed.
However, while the paper is jammed in the second feeding roller set 206, it is rather hard to be removed either along the paper transmitting direction or anti-paper transmitting direction. Paper can be even torn up and left only a portion inside the ADF 200. Hard removing of the paper jammed in the second feeding roller set 206 is mainly caused by the damping produced by the motor 214. Damping comes from the magnetic force between the stator formed by magnet and the rotor formed by coil in the motor 214. The magnetic force generates large resistance while the motor 214 is driven. Further more, damping produced by the motor 214 is enhanced by the speed down design of the gears of the driven machinery. So the jammed paper in the second feeding roller set 206 is hard to be removed no matter in which direction.
It is therefore an object of the invention to provide an ADF, which has special design to prevent damping and the enhancement thereof resulted from the speed down design of the transmission mechanism.
According to the object of the invention, an ADF capable of releasing jammed documents is disclosed. The ADF achieves the object by disconnecting the transmission mechanism between the motor and the feeding roller set. As a result, the damping generated by the motor and the enhancement thereof is avoided.
It is therefore an object of the invention to provide an ADF capable of releasing jammed documents. The ADF capable of releasing jammed documents includes at least a feeding roller set, a motor, and a transmission mechanism connecting the feeding roller and the motor. The motor drives the feeding roller set through the transmission mechanism. The transmission mechanism includes a number of transmission devices. The ADF has the following characteristics. The transmission mechanism thereof includes at least a removable device among the transmission devices. The removable device has an away status and a working status. While the removable device is in the away status, the removable device is away from the transmission mechanism and the transmission mechanism is disconnected so that jammed documents can be removed easily.
According to a further object of the invention, a disconnecting apparatus for installing in an ADF capable of releasing jammed documents is disclosed. The ADF at least includes a transmission mechanism for transmitting the second feeding roller set. The transmission mechanism includes a number of transmission devices and one of the transmission devices is a removable transmission device. The disconnecting apparatus thereof is an elastic device, such as a spring or leaf spring, and a connecting rod. The elastic device pushes the removable transmission device away from the original position from the transmission mechanism and disconnects the transmission mechanism when necessary. The connecting rod is connected to the removable transmission device at one end and connected to the ADF at the other end so that the removable transmission device is able to move backwards and forwards by the aid of the connecting rod.
The ADF further includes an upper cover and a main body. While the upper cover is opened, the elastic device pushes the removable transmission device, such as a gear, away from the transmission mechanism and therefore disconnects the transmission mechanism. The removable transmission device is then in the away status. While the upper cover is closed, the removable transmission device returns back to the original position and is mounted with the adjacent transmission devices. Thus, the transmission mechanism is recovered and is able to transmit the second feeding roller set. The removable transmission device is then in a working status.
It is therefore an object of the invention to provide an ADF capable of releasing jammed documents. The ADF capable of releasing jammed documents includes at least one transmission mechanism connecting the second feeding roller to the motor. The motor drives the second feeding roller set through the transmission mechanism. The transmission mechanism includes a number of transmission devices. The ADF has the following characteristics. The transmission mechanism thereof includes at least a removable device among the transmission devices. The removable device has an away status and a working status. While the removable device is in the away status, the removable device is away from the transmission mechanism and the transmission mechanism is disconnected so that jammed documents can be removed easily. The removable device is removed from the transmission mechanism by the force for releasing the jammed documents.
It is therefore a further object of the invention to provide a disconnecting apparatus for installing in an ADF capable of releasing jammed documents. The ADF capable of releasing jammed documents includes at least one transmission mechanism connecting the second feeding roller to the motor. The motor drives the second feeding roller set through the transmission mechanism. The transmission mechanism includes a number of transmission devices. Among the transmission devices, at least one of which is removable. The disconnecting apparatus is an electromagnetic switch. The electromagnetic switch attracts the removable device away from the original position and thus disconnects the transmission mechanism so that jammed documents can be easily removed. After the jammed documents are removed, the electromagnetic switch pulls the removable device back to the original position and recovers the transmission mechanism to drive the second feeding roller.